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Underfloor Insulation

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ROI
4.2-Years
If you have timber floors, mineral wool insulation* can be used between the joists to insulate your floor.  Assuming this is the only insulation measure installed in your house you can reduce the amount of heat loss through your floor by about a half and can therefore reduce your energy bill by about 7 or 8%.

To do this you need to be able to access under the floor via a trap door or you may have to lift all of the floor boards.  Professionally done this is an expensive job and may cost more than £ 1,000** .  DIY it may cost only a £ 100 for materials, but if t you have to lift your floor boards, it will be a long and difficult DIY task and will probably end up costing more than £ 100 when you find yourself repairing damage caused by lifting boards.  As a DIY task we have estimated the cost at closer to £ 300 for a smaller house.

 

  Approx % energy saving Approx energy saving per year
Gas                       
Electric  (Std)       
Economy 7         
LPG                       
Fuel Oil                   
3 bed house 8%* 1600 kWh £ 72 £ 232 £ 117 £ 123 £ 106
DIY payback time £ 300 install cost  (3 bed house) 4.2 years 1.3 years 2.6 years 2.4 years 2.8 years
Payback time with an installation cost of £ 800** (3 bed house, based on the below comment another quotes) 11.1 years 3.4 years 6.8 years 6.5 years 7.6 years
5 bed house 8%* 2400 kWh £ 108 £ 348 £ 175 £ 185 £ 158
DIY payback time £ 350 (5 bed house) 3.2 years 1 years 2 years 1.9 years 2.2 years
Payback time with an installation cost of £ 1200** (5 bed house, based on the below comment another quotes) 11.1 years 3.4 years 6.8 years 6.5 years 7.6 years

**Please leave a comment if you have more prices for this to get the best figure we can.



 
Comments (6)
6 Sunday, 26 February 2012 15:49
Compost Hugh
Has anyone got a recomendation / advice re spray insulation for suspended floor? I had spray insulation installed on underside of roof very successfully many years ago and zero problems and plenty of pros.
Friday, 16 March 2012 12:03
pip gas and oil
NO! Don't use spray foam as it will trap condensation and rot the boards. Instead, a foil backed solid insulation with the foil on the warm side is best.
Soft insulation will create some condensation within it so will need a high level of ventilation below it.
I know lots of moving air seems energy inefficient, but rotten joists do not repair themselves!
5 Thursday, 19 January 2012 11:51
Mr C. Soulsby
I had a company called "ROOFBOND Ltd" Blackpool, come and do my underfloor space, I have 50 sq meters of underfloor space and paid for 50 sq meters at £40 per sq meter, they only completed 10 sq meters, it took them less than 2 hours work, THEY WILL NOT COME BACK AND FINISH OFF THE WORK IN FOR WHAT THEY HAVE BEEN PAID FOR. my bill was just over 2k for two hours work, i COULD HAVE BOUGHT ALL THE INSULATIONS BOARDS MYSELF FOR LESS THEN £300. I thought this company was ok and checked them out, they also been on "Tomorrow's World" a few years back, or so they cliam! PLEASE if you are thinking of Underfloor insulation! DO NOT USE ROOFBOND LTD THEY WILL RIP YOU OFF!
insulation
4 Sunday, 13 November 2011 17:18
Lynn Henderson
hi i have just had some insulation put in in my bedroom and this site was helpful id like to say the reson why i had insulation put in was not because it was cold, it was because i like taking off my cloths because im always doing u no who... anyway love this site!
3 Thursday, 20 October 2011 21:36
Richard
Thanks Jennifer. That is very useful. I have changed the article accordingly. I think we were quoted on the very high side for this originally. Other prices would be useful if others have them

Cheers richard
2 Tuesday, 18 October 2011 09:17
Jennifer Haye
Just had underfloor insulation done. I think £1500 might be a bit expensive, I was quoted £10-20 pounds per square meter, but this was dependent on my underfloor depth and access. As my underfloor was about 2 feet I was charged £12 per square meter, it cost me £600 for my 3 bed semi. I went with Andy at draughtyfloors.co.uk, really pleased it's really taken away the chilly feet and draughty feeling I had in the lounge, don't need the fire on now!
feedback
1 Tuesday, 05 October 2010 07:38
I have a site about Underfloor Insulation. So, your information, I think, very much helpful for me. Thank you for nice posting.

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Comments, category: "Heat Loss and Insulation"


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